Page 552 - IJB-9-6

International Journal of Bioprinting 3D printing of PCL-ceramic composite scaffolds

time. After that, cells were washed 2 times with PBS and non-Newtonian fluid behavior at higher shear rates. The
treated with 10% (v/v) AB reagent in the appropriate non-Newtonian behavior represents a shear-thinning fluid
culture medium for 4 h. Multiple aliquots of the assay as the shear rate increases beyond 80 s. The shear stress
solutions were obtained and measured for fluorescence increased with an increase in the content of CMP, in the
using a spectrophotometer with excitation at 530 nm and following order PMC-0 < PMC-5 < PMC-10 < PMC-15.
emission at 590 nm. The following equation was used to With the addition of the CMP particles, the viscosity of
calculate the viability of cells: the PMCs materials increased because of the interaction
between the polymeric matrix (PCL) and the ceramic
Fluorescence of the samples particles (CMP). The increase in the shear stress is due
− Fluorescence of the blank to the increase in the microparticle content of ceramic
Cell viability = × 100%
Fluorescence of the control material in the polymer matrix, which leads to a higher
− Fluorescence of the blank resistance to the flow of fluid [58,59] . Higher shear stress for
increased PCL-CMP blends indicates an elasticity higher
LDH assay was carried out with the stored medium than that of pure PCL. The rheological behavior observed
collected earlier. herein is vital as the bioprinter needs to be operated
by varying parameters, such as deposition line speed,
2.4.7. Statistical analysis extrusion pressure, and nozzle size, to accommodate the
Statistical analysis was performed using Minitab statistical shear-thinning behavior of the biomaterial being bio-
software. Data are expressed as mean ± standard deviation. printed. Moreover, higher extrusion pressures are needed
Comparisons of groups were performed using one-way to deposit higher PCL-CMP blends to maintain consistent
analysis of variance (ANOVA) and Tukey’s post hoc test. scaffold geometries.
Significance levels were set at P < 0.05. 3.2. Characterization of ceramic powder

3. Results and discussion The as-prepared CMP ceramic was used for incorporation
3.1. Rheology measurements into the 3D-printed PCL scaffolds. SEM image (Figure 4)
shows that the ceramic was a mixture of clay-like
The rheological properties of the materials were studied Ca (PO ) and spindle-shaped Mg (PO ) particles .
[60]
4 2
3
3
4 2
to investigate the effect of CMP on the PCL matrix. The About 2- – 5-micron (length) Mg (PO ) crystals were seen
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3
rheological measurements of the PCL and composite in embedded into Ca (PO ) substances. The XRD pattern for
3
4 2
terms of shear rate and shear stress are shown in Figure 3. CMP is shown in Figure 5 (left). XRD data for the particles,
All tests were performed in flow sweep mode across a range with peaks, are consistent with the known crystallographic
of shear rates from 0.1 to 120 s . PMC-0, PMC-5, PMC-10, planes of both phosphates. Mg (PO ) peaks are assigned
−1
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3
and PMC-15 exhibit a Newtonian region followed by by cross marks (x), and Ca (PO ) peaks are assigned
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3
by an asterisk (*) marks . Figure 5 (right) shows the
[60]
FT-IR spectra of the ceramic powder. Absorption bands
at 1060 cm and 970 cm were ascribed to PO , and
3-
-1
-1
4

Figure 3. Rheology characteristics of PMCs suspensions. An increase in
the microparticle content of ceramic material in the PCL matrix exhibit a Figure 4. SEM image of as-prepared ceramic powder. Clay-like substances
non-Newtonian fluid behavior at higher shear rates. are Ca (PO ) and spindle-shaped substances are Mg (PO ) .
4 2
3
4 2
3
Volume 9 Issue 6 (2023) 544 https://doi.org/10.36922/ijb.0196